Five hundred twenty patients with de novo non-lymphocytic leukemia (ANLL) were classified according to morphocytochemical FAB criteria and then immunophenotyped using a set of 20 monoclonal antibodies (MoAb) of VI series. It was demonstrated that immunophenotyping increased the proportion of properly classified leukemias from 87% after morphocytochemical evaluation up to 97.5%. A first line diagnostic set was proposed for ANLL consisting of MoAbs detecting the following cell differentiation antigens: CDw65 (VIM2)--as a screening marker for the whole ANLL group, CD14 (VIM12)--as an indicator characteristic for M4 and M5 FAB subtypes, glycophorin A (VIEG4)--helpful in identification of erythroleukemia, CD15 (VIMD5)--which has a prognostic significance and CD41 (VIPI1)--important for identification of megacarioblastic M7 subtype. MoAbs detecting CD11b, CD61 and Ia-Dr may be used as the second line reagents.